How do I open multiple images in Gimp?

I'm having trouble opening up multiple pictures with Gimp ever since the new High Sierra macOS (10.13.1) update. Whereas in the past, I highlight multiple pictures, right click, click open with > Gimp and all the pictures would open in a single program. I use Gimp version 2.8.14

Now, when I try the same thing, only one picture opens up. Then when I open up each image with Gimp individually, it opens in a new, SEPARATE Gimp program. So there's multiple Gimp icons on my dock. Each image has it's own corresponding toolbar, etc.

This creates much more of a headache for getting work done in Gimp. Any ideas how to fix this?